This invention relates to a novel polymer, and to a method of making the same. More particularly, the invention relates to the class of polymers which have a plurality of amide, imide and ester groups therein and are soluble in cresylic acid. Additionally, and more particularly, the invention relates to magnet wire enamels, inasmuch as the novel polymer of the invention has all of the physical, mechanical, chemical and electrical properties of a good magnet wire insulation material.
Essentially linear polyester polymers materials have long been available. Such materials have heretofore been used as magnet wire insulation materials. Both thermoplastic and thermosettable essential linear polyester resin materials have been heretofore proposed. See for example:
______________________________________ British Patent No. 978,717 U.S. Pat. No. 3,293,248 British Patent No. 1,115,919 U.S. Pat. No. 3,297,785 Canadian Patent No. 706,940 U.S. Pat. No. 3,312,573 Canadian Patent No. 781,993 U.S. Pat. No. 3,342,780 French Patent No. 1,416,443 U.S. Pat. No. 3,390,131 U.S. Pat. No. 2,268,586 U.S. Pat. No. 3,428,426 U.S. Pat. No. 2,333,639 U.S. Pat. No. 3,445,477 U.S. Pat. No. 2,686,739 U.S. Pat. No. 3,446,758 U.S. Pat. No. 2,691,006 U.S. Pat. No. 3,448,089 U.S. Pat. No. 2,889,304 U.S. Pat. No. 3,480,589 U.S. Pat. No. 2,936,296 U.S. Pat. No. 3,489,696 U.S. Pat. No. 3,022,200 U.S. Pat. No. 3,518,219 U.S. Pat. No. 3,141,859 U.S. Pat. No. 3,518,230 U.S. Pat. No. 3,179,634 U.S. Pat. No. 3,553,215 U.S. Pat. No. 3,201,276 U.S. Pat. No. 3,576,774 U.S. Pat. No. 3,211,585 U.S. Pat. No. 3,578,639 U.S. Pat. No. 3,240,626 U.S. Pat. No. 3,699,082 U.S. Pat. No. 3,249,578 U.S. Pat. No. 3,790,530 ______________________________________
Numerous polyamide polymers, polyamide-imide polymers and polyimide polymers have also been proposed. These polymers generally have better thermal properties than the polyester polymers, but are appreciably more expensive than the polyester polymers. Thus, while these polymers also have been used as magnet wire enamels, their use has been limited to applications which can tolerate the increased cost thereof. Such polymers have also been disclosed; see for example:
______________________________________ British Patent No. 570,858 U.S. Pat. No. 3,347,828 British Patent No. 627,205 U.S. Pat. No. 3,445,477 British Patent No. 810,489 U.S. Pat. No. 3,451,848 British Patent No. 1,009,956 U.S. Pat. No. 3,471,444 British Patent No. 1,060,159 U.S. Pat. No. 3,472,815 British Patent No. 1,155,230 U.S. Pat. No. 3,475,212 British Patent No. 1,160,097 U.S. Pat. No. 3,485,796 British Patent No. 1,168,978 U.S. Pat. No. 3,489,696 British Patent No. 1,171,242 U.S. Pat. No. 3,493,540 British Patent No. 1,175,555 U.S. Pat. No. 3,509,106 British Patent No. 1,217,041 U.S. Pat. No. 3,518,219 British Patent No. 1,220,590 U.S. Pat. No. 3,518,230 British Patent No. 1,234,252 U.S. Pat. No. 3,539,537 Canadian Patent No. 701,460 U.S. Pat. No. 3,541,038 French Patent No. 1,473,600 U.S. Pat. No. 3,546,152 U.S. Pat. No. 2,268,586 U.S. Pat. No. 3,547,895 U.S. Pat. No. 2,621,168 U.S. Pat. No. 3,553,159 U.S. Pat. No. 3,179,635 U.S. Pat. No. 3,554,984 U.S. Pat. No. 3,179,639 U.S. Pat. No. 3,562,217 U.S. Pat. No. 3,260,691 U.S. Pat. No. 3,575,891 U.S. Pat. No. 3,300,420 U.S. Pat. No. 3,578,639 U.S. Pat. No. 3,314,923 U.S. Pat. No. 3,592,789 U.S. Pat. No. 3,696,077 U.S. Pat. No. 3,790,530 ______________________________________
The demand for new polymers for use as magnet wire insulation materials which have higher and more reliable thermal life, while at the same time, are less expensive to manufacture and to apply than the polyamide, polyamide-imide, and polyimide polymers continues. To meet this demand, there had been proposed several modified polyamide, polyimide and polyester polymer materials. For the most part, these materials are polyamide ester resin materials, polyimide ester resin materials or polyamide-imide-ester resin materials. See for example:
______________________________________ British Patent No. 1,242,715 U.S. Pat. No. 3,425,866 Canadian Pat. No. 771,126 U.S. Pat. No. 3,426,098 U.S. Pat. No. 2,547,113 U.S. Pat. No. 3,428,486 U.S. Pat. No. 2,626,223 U.S. Pat. No. 3,458,480 U.S. Pat. No. 2,777,830 U.S. Pat. No. 3,493,544 U.S. Pat. No. 2,821,517 U.S. Pat. No. 3,505,272 U.S. Pat. No. 3,136,738 U.S. Pat. No. 3,551,383 U.S. Pat. No. 3,255,069 U.S. Pat. No. 3,555,113 U.S. Pat. No. 3,338,743 U.S. Pat. No. 3,578,638 U.S. Pat. No. 3,354,126 U.S. Pat. No. 3,699,082 U.S. Pat. No. 3,361,593 U.S. Pat. No. 3,793,250 U.S. Pat. No. 3,390,118 ______________________________________
In general, some such materials are thermoplastic, some are thermosettable materials, some are cross-linked thermoplastic materials and some are cross-linked thermosettable materials. For the most part all such materials contain both aliphatic and aromatic groups. In general, the linear polymers have more flexibility than the nonlinear, cross-linked materials, and the totally aromatic polymers have a higher and more reliable thermal life, but are more expensive than the totally aliphatic polymers. Thus, each of the above-identified modified polyamide, polyester, and polyimide polymers represent compromises in thermal life, cost, flexibility, and other physical, mechanical, chemical and electrical properties.
In recent years, due to new and different applications of magnet wire, the demand for higher and more reliable thermal life has increased considerably. At the same time, the demand for lower costs and decreased processing times has also increased. It is therefore desirable to provide an improved magnet wire enamel having a higher more reliable thermal life, an increased resistance to thermal overloads which at the same time has all of the required mechanical, physical, chemical and electrical properties required for most major uses as insulation material, which can be applied in an economical and rapid manner. It is also desirable that such a resin substantially comprise a polymer having ester, imide, and amide groups therein since the inherent properties thereof are well known to manufacturers of insulated products. Further, it is highly desirable that such a magnet wire insulation material be made from readily available and well known starting materials, and soluble in conventional solvents such as cresylic acid.